That looks like Sandhill Ranch T Red? I went to my first ever vintage race there back in 1986. Dick Mann looked after me so well, supplying a CZ to ride and inviting me to stay at his house in Richmond, which I naturally took up. I met Lackey, Pomeroy and had a Margarita with the Dave Aldana .The pro race was won by Little John Hateley ahead of Doug Grant and Ron Pomeroy. That event holds great memories for me.
I've got a soft spot for those RM500 Suzukis. A mate has one cocked up for dirt track, on methanol and ported by Gary Treadwell. It was one of the scariest dirt bikes I've ever ridden. He still owns it today but won't sell it. When I bought a bunch of Maicos from Karl Kramer a few years ago he offered me Anthony old Gunters RM500 for an extra $1000. I should have taken it but I was out of money. It had some trick bits bits including (I think) a set of upside down Simons forks like those on Lackeys bike. I wonder where it went?